Lactoferrin is a glycoprotein that has physiological and biological characteristics such as bactericidal, growth stimulatory, iron carrying activity, immune modulation, and specific reaction to membrane receptors.
The structure of human lactoferrin is composed of 681 amino acid residues. There is an iron-binding site in between the domains of one of the two lobes. Lactoferrin is known to have immuno-stimulatory effect and antibacterial activity. Also, it is reported that the peptides or polypeptides derived from lactoferrin are superior to lactoferrin itself in antibacterial activity and stability (U.S. Pat. No. 5,304,633; 5,571,697). Therefore, lactoferrin polypeptide is a good additive for infant formulas and animal feed or drugs due to its bacteriostatic, cell growth stimulatory or inflammation inhibitory effects.
Lactoferrin polypeptides have been isolated mainly from milk serum. Recently, mass production of polypeptides by genetic engineering have been attempted. Ward and Piddington have produced 2 g/l quantity of recombinant lactoferrin in Aspergillus oryzae using a glucoamylase promoter (Ward, P. P. et.al., Biotechnology, 13:498-503 (1995)). Qianwa reported that 1.5xcx9c2.0 mg/l of recombinant human lactoferrin was obtained by expressing it in the form of a fusion protein between a yeast invertase and human lactoferrin by using a chelatin promoter in Saccharomyces cerevisiae (Qianwa Liang et.al., J. Agric. Food. Chem. 41:1800-1907 (1989)). It was discussed that the recombinant lactoferrin synthesized from S. cerevisiae had additional sugar units, and the yield was not reproducible. In the case of producing lactoferrin or its antibacterial peptide derivatives by using genetic engineering techniques, expressed lactoferrin or antibacterial peptide could slow down the growth of or even kill the host microorganism. To overcome this problem, it is reported that the antibacterial peptide was expressed in the form of a fusion peptide. In U.S. Pat. No. 5,571,697, antibacterial polypeptide derived from lactoferrin was expressed as a fusion protein in Aspergillus.
The present invention provides a method to mass-produce lactoferrin polypeptide from microorganisms.
The present invention provides a method to mass-produce lactoferrin polypeptide alone from microorganisms.
The present invention provides a novel germ strain, which is resistant against lactoferrin polypeptide.
The present invention provides a germ strain that produces lactoferrin polypeptide.